Acne is a multifactorial disease with alterations in sebum excretion and composition and alterations in androgen metabolism in skin recognized as agents in its etiopathogenesis. The present longitudinal prospective study is being conducted to determine whether certain changes in sebum composition and urinary androgen excretion can be used as early markers and can be correlated with the appearance of clinically significant acne in a study population of 65 subjects ages 9-14. Fractions of sebum have been shown to be comedogenic and although the absolute amount of sebum excreted cannot be correlated with acne, it is probable that the relative changes taking place in sebum composition predispose susceptible subjects to develop acne. This research offers a possible means to elucidate the alterations in sebum composition which trigger the development of acne in certain individuals. In addition, important endocrinological data will be obtained to correlate peripheral androgen metabolism in skin with androgen excretion in the urine and its effect on sebaceous gland development and the course of adolescent acne.